1. Technical Field
The present invention relates to organic electroluminescent (EL) devices and electronic apparatuses.
2. Related Art
Organic EL devices having numerous organic EL elements on substrates are known in the related art. An organic EL device includes a planarizing layer covering components, such as thin-film transistors (TFTs) and wiring lines, formed on a substrate, electrodes (anodes) formed on the planarizing layer, a bank having openings separating the electrodes, functional layers formed in the openings of the bank, and an electrode (cathode) formed so as to cover the functional layers.
Extensive research and development has been conducted on organic EL devices with the growing need for low-power, lightweight flat displays, and various production methods and various device configurations with improved display characteristics have been proposed (see, for example, the specification of Japanese Patent No. 3,328,297 and JP-A-2003-123988).
For example, an organic EL device in the related art has a problem in that it cannot provide sufficient color reproducibility when applied to a display because light output from light-emitting layers has a wide spectral peak and low luminous intensity. Accordingly, it has been proposed to provide an optical cavity structure including reflective layers formed between a substrate and anodes and a transflective cathode formed on the output side of light-emitting layers so that light emitted from the light-emitting layers resonates between the reflective layers and the cathode (see JP-A-2008-282602). Because the reflective layers are often formed of a metal material, an insulating layer is formed between the anodes and the reflective layers to prevent a short circuit therebetween.
With the above structure, an organic EL device can output selectively amplified light of resonant wavelength toward the observer. This allows the use of light with a narrow spectral peak and high luminous intensity for display purposes, thus improving the color reproducibility of displays.
A planarizing layer in an organic EL device is usually formed by photolithography after dissolving a resin or resin precursor in a solvent and applying the solution. Therefore, the planarizing layer may contain residual solvent used in the formation of the planarizing layer. In addition, the planarizing layer is exposed to treatment liquids such as resist strippers used in the formation of layers other than the planarizing layer. Therefore, the planarizing layer may be impregnated with such treatment liquids.
The solvent and treatment liquid contained in the planarizing layer vaporizes with drive heat from the organic EL device or changes in the ambient temperature of the use environment. Such vaporization can also occur after the formation of highly hermetic layers, such as anodes and an insulating film formed of inorganic materials, on the planarizing layer. If vaporization occurs in the planarizing layer covered with the highly hermetic layers, the generated gas cannot be released and may damage the anodes and the insulating film as a result of volume expansion.
If the anodes are damaged, dark spots are formed at the damaged sites because no current flows there, thus degrading display quality. In addition, the generated gas may leak from the damaged sites and degrade functional layers such as light-emitting layers. This causes dark spots that grow around the damaged sites and spread as dead regions, thus significantly shortening a product life.